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The decline of pollinator insects in various parts of the world has increased the interest in studies on bee sampling. Because pollinator management and conservation policies depend on data representing their communities, knowledge of the systematic bias of sampling methods in relation to surrounding habitat is fundamental. This study examined the performance of standardized transect walks and colored pan traps considering differences in bee species richness, diversity, and composition, and the potential bias due to a different availability of floral sources throughout seasons. The study was conducted in a minor outlying island (Asinara, Italy), a natural park characterized by the prevalence of natural or semi-natural habitats and an Oceanic Pluviseasonal Mediterranean bioclimate. We found that transect and pan trap methods reflected different bee communities based on taxonomic families, genera, and species. In general, the transect method captured more varied samples than pan traps, despite the significantly lower number of individuals captured on transects. Moreover, pan traps captured more bees as floral abundance decreased, whereas transects showed greater bee abundance, richness, and diversity with increasing floral resource availability. In addition, 18 species out of the 68 observed in total were caught exclusively with pan traps, especially in July–October, when transect catches decreased due to substantial bloom reduction. Therefore, alternating the two methods according to season (i.e., transect in late winter-spring and pan trap in summer-autumn) might be the most suitable trade-off to obtain a better representation of the bee community by limiting sampling efforts and the negative impact on bee fauna. [ABSTRACT FROM AUTHOR]

The interspecific transmission of pathogens can occur frequently in the environment. Among wild bees, the main spillover cases are caused by pathogens associated with Apis mellifera, whose colonies can act as reservoirs. Due to the limited availability of data in Italy, it is challenging to accurately assess the impact and implications of this phenomenon on the wild bee populations. In this study, a total of 3372 bees were sampled from 11 Italian regions within the BeeNet project, evaluating the prevalence and the abundance of the major honey bee pathogens (DWV, BQCV, ABPV, CBPV, KBV, Nosema ceranae, Ascosphaera apis, Crithidia mellificae, Lotmaria passim, Crithidia bombi). The 68.4% of samples were positive for at least one pathogen. DWV, BQCV, N. ceranae and CBPV showed the highest prevalence and abundance values, confirming them as the most prevalent pathogens spread in the environment. For these pathogens, Andrena, Bombus, Eucera and Seladonia showed the highest mean prevalence and abundance values. Generally, time trends showed a prevalence and abundance decrease from April to July. In order to predict the risk of infection among wild bees, statistical models were developed. A low influence of apiary density on pathogen occurrence was observed, while meteorological conditions and agricultural management showed a greater impact on pathogen persistence in the environment. Social and biological traits of wild bees also contributed to defining a higher risk of infection for bivoltine, communal, mining and oligolectic bees. Out of all the samples tested, 40.5% were co-infected with two or more pathogens. In some cases, individuals were simultaneously infected with up to five different pathogens. It is essential to increase knowledge about the transmission of pathogens among wild bees to understand dynamics, impact and effects on pollinator populations. Implementing concrete plans for the conservation of wild bee species is important to ensure the health of wild and human-managed bees within a One-Health perspective. [ABSTRACT FROM AUTHOR]

Context: The reduction in the abundance and diversity of flowering plant species, mainly due to landscape alteration and consequent habitat loss, negatively affects honey bee populations and is the main driver of their decline. To safeguard pollination service and food security, we need to know how landscape characteristics affect the availability of pollen sources and consequently colony performance across seasons. Objectives: We therefore here explore how seasonality, percentage of semi-natural habitat cover and compositional landscape heterogeneity affect the abundance, richness, diversity and composition of pollen collected by honey bees and the development of their colonies in a Mediterranean area where agro-sylvo-pastoral systems are widely spread. Methods: For the purpose of our study, pollen samples were collected over a year from colonies of Apis mellifera placed in four sampling sites selected across a gradient of landscape heterogeneity and where semi-natural habitats were predominant at various levels within an agro-sylvo-pastoral zone. Simultaneously, the extension of the sealed brood of the same colonies was periodically evaluated. Results: We found that the amount of pollen collected by honey bees was positively correlated with the percentage of semi-natural habitat cover and that increasing habitat diversity at the landscape level had a significant positive effect on the richness and diversity of pollen collected by honey bees. In addition, season significantly affected the amount, diversity and composition of pollen collected by honey bees. Furthermore, bee colony growth was positively correlated with richness, diversity and amount of pollen collected by honey bees. Conclusion: Our study highlights the importance of an abundant and diverse pollen diet for honey bee colony development, which in agro-sylvo-pastoral systems seems to be ensured by a heterogeneous landscape dominated by different types of semi-natural habitats. [ABSTRACT FROM AUTHOR]

Self-medication plays a major role in the behavioral defense against pathogens and parasites that animals have developed during evolution. The conditions defining this adaptive behavior are: (1) contact with the substance in question must be deliberate; (2) the substance must be detrimental to one or more parasites; (3) the detrimental effect on parasites must lead to increased host fitness. Recent studies have shown that A. mellifera colonies are able to increase resin foraging rates when infested by V. destructor, whereas further investigations are needed for evidence of parasite and host fitness. In order to understand whether Varroa-infested colonies could benefit from increasing levels of resin, we carried out laboratory bioassays to investigate the effects of propolis on the fitness of infested workers. The longevity and energetic stress of adult bees kept in experimental cages and artificially infested with the mite were thus monitored over time. At the same time, in vitro experiments were performed to study the contact effects of crude propolis on Varroa mites. Our results clearly demonstrate the positive effects of raw propolis on the lifespan of Varroa-infested adult bees. A low narcoleptic effect (19-22%) of raw propolis on phoretic mites after 5 h was also observed. In terms of energetic stress, we found no differences between Varroa-free and Varroa-infested bees in terms of the daily sucrose solution demand. Our findings seem to confirm the hypothesis that resin collection and propolis use in the hive represent an example of self-medication behavior in social insects. [ABSTRACT FROM AUTHOR]